Electric plug



May 23'; 1939. N. cHlRELsTElN 'ELECTRIC PLUG Fileq Aug. 11. 1957 INVENTQR NATHAN H/REL srE//v ATTORNEY Patented May 23, 1939 UNITED STATES PATENT OFFICE 2 Claims.

My invention relates to electric plug constructions. The object of my invention is to provide an Aimproved male plug portion of a plug and socket combination, which maybe easily coupled with the female member in which the sockets are formed, and which may be easily'removed therefrom without danger of becoming permanently` locked in coupled relation.

A further object is to provide a blade construcm tion of sheet metal that will be flexible, and

strong enough to maintain its form from permanent distortion when subjected to stress in the act of coupling and uncoupling the plug from the female or lsocket member of the plug con- -ld struction.

. In the Patent No. 2,037,562 dated April 14, 1936, granted to me, l2 have disclosed a construction in which a thin blade is used to provide resiliency, which is formed by folding the blades at their 2@ free ends to provide branch portions which serve to eii'ect good contact with the terminal members of the female portion of a plug.

In said patent an opening is formed in the branch adjacent its point of junction with'the blade, which serves to weaken the stiffness of the branch and cause it to bend and thus provide a shoulder'such as illustrated in Fig. 1 of thel with a female member that is formed with inner walls such as I 3-illustrated in the present application. l

The standard thickness of a blade is one-sixteenth of an inch and the width of the slot of the vfemale member varies between three and four-thirty-seconds of an inch, thus allowing in many cases but Vone-thirty-second of an inch for clearance.

The offset portionof the blade between its point of junction and the adjacent end of the opening, increases the thickness of. the blade as a whole at this point, and due to its width and stiiIness it is sometimes difcult to remove it from the sockeiwhen the socket opening is of mini-y mum width.

In .the present construction the blades are made of resilient metal, eachmblade portion havling a thickness of about one-thirty-second of an inch and about one-quarter of an inch in width, and made from a strip which is bent back upon itself the full length of the blade to form a blade 55 of two layers, one or both of which may have end of the branch, permits of more or less rela-v (cl, 11s- 361) a branch portion extending outwardly therefrom, and formed integral therewith at a point near its free end.

Each branch portion is formed integral with the bladek and struck out fromits Jniddle part and is therefore of less width and length than that of the blade, and by reason of its reduced width and thickness will yield easily under pressure in the act of coupling or uncoupling the plug from the socket member.

Referring to the drawing which forms a part ofthe present specification:

Fig. l is a vertical sectional View of a plug construction in which the plug portion is shown with its blades partlyinserted in the sockets of the female'portion, and illustrates the action of the blades in passing thru the slots formed in the face of the socket portion.

2 is a vertical sectional View of the plug and a part .of the socket portion as they appear in coupled relation;

Fig. 3 is a view of the face end of the plug.

Fig. '4 is a perspective yiew of a blade member constructed as illustrated in Fig. 1.

Fig. 5 is an elevational View of a blade member formed to provide a space or slot at each side of the branch member to insure'freedom of movement of the branch when pressed thru the opening formed in the stem of the blade.

with two branch portions.

Fig. 7 is a perspective view of a blade construction, the branch of which is 'formed Without a shoulder near its free end, one half of the bladeA remainingimperforate opposite the opening made in the opposite side in forming the branch.-

Fig. 8 is a Vertical sectional view showing the blade illustrated in Fig. '7 located in a portion of a socket member of a plug, and illlustrating the curvature of the branch portion when inserted in Fig. 6 is a perspective view of a blade formed,

fiormeci therein; the drawing showing the con- A struction on an enlarged scale.

-lG-IB respectively, indicate the terminal conductors of a standard socket construction.

The body of the plug lll is made of insulating material and formed to provide a central passage l1, and an inner plane surface I8, in which recesses |9|9 respectively are formed to receive the screws 20.

The blades 2|-2I respectively are each provided with a iiat base portion 22 and the blades extend atan angle thereto as shown at 23 and each blade being bent back upon itself at its outer free end 24, and bent to form an extension 25 thru which a screw 20 extends to secure them to the body portion I0.

The extension 25 stifr'ens and strengthens the base portion of the blade and prevents it from being easily bent under strain in the act of removing the plug from the socket member.

In all of the figures except Fig. 6, I have shown a branch 26 struck out from a blade 2| from one side strip only.

In Fig. 6 I show a branch struck out from both side strips forming the blade proper intermediate its edges.

This construction insures 'good contact with the blade of the socket member regardless of which side thereof contacts the blade of the plug member, and yields easily in the act of removal from the socket,A and yet holds rmly in the socket under normal operating conditions.

If desired, the shoulders 3| may be dispensed with and the branch or branches formed as illustrated in Fig. 7 for use with socket members that `have no inner wall such as I3, but where a shoulder is formed on a branch I prefer to provide an opening 32 to allow the end of the branch to extend therethru in the act of coupling and uncoupling the body portions. l

I prefer to make the branches somewhat wider at their points of junction with the blades and therefore provide a stiffening efect'which gradually becomes less toward the end 29 which extends to nearly the face of the female member d when the body portions of the plug are coupled, the free end resting in the slot as shown in Figures 2 and 8.

Each branch shown in Figures 1 to 6, inclusive,-

is bent near its free end and extends inwardly toward the blade as shown at 3|, and the opposite member. 2| is formed vwith an aperture 32 into which the free end of the branch may enter in the act of inserting or removing the plug from the sockets.

' This construction permits a greater movement of the branch inwardly and is suflicient to prevent the blade from jambing inthe slot when it is very narrow in` width. A further improvement is that of forming a slot or space 33 ,atl each side of the branch to prevent contact of the adjacent edges of the wall of the blade in case the breach becomes slightly bent in use, such bending causing the branch to wedge in the slot of the stem and preventing the withdrawal of the blades from the sockets.

In the construction shown in Figure 6, I prefer to make one of the branches a little shorter than the other to allow one free'end to overlap the adjacent end of the other branch and provide for a greater degree of movement toward each other in the act of coupling or uncoupling the body portions.

blade from bending out of shape in the lact of pulling it f rom the socket, or from being easily bent in handling.

Having thus' described my invention I claim as new:

1. An attachment plug comprising a body portion oi' insulating material having a fiat face and a pair of at contact blades extending outwardly of the at face and spaced apart a distance corresponding to the separation between the socket openings of a standard receptacle, each of said blades being formed from a strip of thin resilient metal bent upon itself to provide a blade of two layers. one of said layers being formed with an aperture and the other layer having a branch struck therefrom intermediate its side edges and projecting outwardly from said layer, said branch having an offset shoulder adjacent its free end, said branch extending from adjacent the free end of the blade and the free end of the branch lbeing spaced from the fiat face of said body portion with the shoulder at the free end of the branch movable to enter the blade layer aperture during the `attachment of the plug to a standard receptacle.

branches being spaced from and terminating ad-v jacent the hat face ofsaid body portion and a shoulder adjacent the free end of each branch normally offset from the adjacent side of the blade.

NATHAN CHIRELSTEIN. 

